Above a roof of a railway vehicle, there is a collector shoe supported via a pantograph to take in electric power from an overhead line. Specifically, a slider, which is supported on the top surface of the collector shoe, and which is made from conductive material such as sintered metal, is elastically pressed against a lower edge of the overhead line to take in electric power from this overhead line to the vehicle. Among such pantograph and collector shoe devices, the structure of those used in high speed railway vehicles such as a super express railway vehicle differs from the structure of those used in a conventional railway vehicles, in giving consideration to reduction of airflow noise generated when the vehicle is traveling, and the tracking performance on the overhead line.
FIG. 19 shows a collector shoe device disclosed in Patent Document 1 among the collector shoe devices that have been developed for a high speed railway vehicle in consideration of such points. In the case of this conventional structure, on an upper end section of an upper frame 1 that constructs the pantograph, there is supported a middle section of a ceiling pipe 2, and around this ceiling pipe 2, a hollow shoe body 3 is elastically supported allowing some slight free rising and falling movement. Accordingly, within this shoe body 3, there are provided linear shafts 4, springs 5, and conducting wires 6 for conducting electricity. A slider 7 is installed on a top surface of the shoe body 3.
As a result of such structure, even when driven at a high speed, air does not flow around the ceiling pipe 2, the linear shafts 4, the springs 5, and the conducting wires 6, allowing a corresponding reduction in airflow noise. Moreover, in, the case where the vertical position of the overhead line changes finely, the shoe body 3 shifts with respect to the ceiling pipe 2 to track the change of the overhead line position. In other words, this ceiling pipe 2 does not need to shift in the vertical direction. Therefore, the inertial mass of the portion that shifts in the vertical direction for tracking the overhead line can be kept low, and the tracking performance of this portion on the overhead line can be made excellent. If the vertical position of the overhead line changes significantly, the upper frame 1 is raised and lowered to allow the slider 7 to track this overhead line, A ceiling pipe in the field of collector shoe devices for railway vehicles refers to a member in a support frame form arranged in the crosswise direction of the vehicle on the top end section of a pantograph. Conventionally it was actually formed in a pipe shape (in the case of a rhombic shaped pantograph that was used for a conventional railway vehicle). However, it is not limited to a pipe shape (especially for a high speed railway vehicle).
In the case of the conventional structure disclosed in Patent Document 1 mentioned above, compared to its prior art structure, airflow noise can be reduced and tracking performance on the overhead line can be improved. However, in the point of improving the tracking performance on the overhead line, there is still scope for improvement. Specifically, in the conventional structure, when the vertical position of the overhead line finely changes, the shoe body 3 and a pair of frame rods 8 on the right and left fixed on this shoe body 3 rise and fall together with the entire slider 7. Therefore it is inevitable that the inertial mass is great despite the ceiling pipe 3 and the upper frame 1 not being included. Accordingly, in the case of further increasing the speed of the railway vehicle, it is possible that the contact performance between the top surface of the slider 7 and the overhead line (the performance of retaining an appropriate contact condition) decreases. If the elastic force of a spring assembled in the pantograph to give the upper frame 1 standing direction elasticity, and the elastic force of the respective springs 5 for giving the ceiling pipe 2 a rising direction elastic force with respect to the shoe body 3, are increased, the tracking performance can be improved. However, in this case, since the contact surface pressure between the top surface of the slider 7 and the overhead line becomes greater, resulting in significant wear in the slider 7 and the overhead line, it is not preferable.
On the other hand, in order to improve the tracking performance on the overhead line, a structure exaggeratedly shown in FIG. 20 may be considered. Specifically, a slider 7a that comes in contact with the overhead line, and a slider support plate that supports this slider 7a from below elastically deform (bend) in a concave shape due to a load applied due to the contact with the overhead line. Alternatively, the slider 7a comprises a plurality of slider elements divided in the crosswise direction of the vehicle and arranged in series in this crosswise direction, and a slider support plate that supports these respective slider elements elastically deforms as described above. A structure in which both of the lengthwise direction end sections of this slider 7a or the slider support plate are supported on the shoe body not shown in the drawing) may be considered. In such a construction, when the vertical position of the overhead line finely shifts, the slider 7a and the slider support plate elastically deform in response to the fine vertical movement of this overhead line, and contact performance between the overhead line and the slider 7a can be well retained. However, in the case of such a structure shown in FIG. 20, since both of the lengthwise direction end sections of the slider 7a or the slider support plate are supported on the shoe body, an elastic deformation amount (bend amount) in the vertical direction in both of the end sections of this slider 7a or the slider support plate cannot be easily ensured. That is to say, a vertical direction shift (stroke) amount of the top surfaces of both of the end sections of this slider 7a due to the elastic deformation inevitably becomes smaller. Because of this, in the case where the overhead line is positioned in the proximity of both of the end sections of the slider 7a, the effect of improvement in a tracking performance of this slider or the slider support plate due to elastic deformation cannot be easily obtained. In other words, in a state where the overhead line is positioned in the proximity of both of the lengthwise direction end sections of the slider 7a, when the overhead line finely shifts in the vertical direction, the shoe body and the upper frame of the pantograph that supports this shoe body are raised and lowered together with the slider 7a. Therefore, the inertial mass is great as is the case with the structure shown in FIG. 19 mentioned above, and there is a possibility that the contact performance at both of the end sections of this slider 7a cannot be well retained.
Patent Document 1: Japanese Patent Publication No. 3297355